This is a situation where I need the help of you OSnews readers who are experienced with low-level development on ARM, SPARC, PowerPC, MIPS, and other hardware architectures we have on computers nowadays. The issue is that I'm currently designing the part of my hobby kernel which takes care of interrupts. Although I mostly work on x86 at the moment, I'd like to keep this code portable to other hardware architectures in the future. To do that, I have to know how interrupt handling works on as much HW architectures as possible.

Well, if you want this, maybe you should review the source code and docs of NetBSD... it runs on many platforms, it's something already done, the code maybe has some comments or doc for u to check... I would do.